1. Field of the Invention
The present invention relates to a light-guiding structure. In particular, this invention relates to a light-guiding structure that uses the light-entering interface and the ditch to uniformly spread the light. Thereby, the light is uniformly spread at the light-entering side of the light-guiding plate, and the light is uniformly emitted from the light-emitting surface of the light-guiding plate and the illumination is enhanced.
2. Description of the Related Art
A backlight device includes a light-guiding module, a diffusion sheet, and a prism sheet (or a brightness enhancement film), etc. The light-guiding module includes a frame, a light source, a light-guiding plate, and a reflection cover.
The backlight device provides a backlight source to an apparatus, such as an LCD, a negative scanner, a slide projector, or an overhead projector, etc. The LCD is the major market for the backlight device, and the market rapidly grows as the LCD has been developed.
The backlight device uses a light-guiding plate to guide a spontaneous light source, such as a CCFL or an LED, and generates a big, uniform and bright light-emitting surface. The light of the spontaneous light source is reflected by the reflection cover and then emits from the light-emitting surface of the light-guiding plate. Therefore, the light uniformly emitted from the light-emitting surface is a basic factor for the backlight device.
Reference is made to FIGS. 1 and 2, which show the light-guiding structure of the prior art. The light-guiding structure includes a light-guiding plate 12a, and an LED set 14a. The LED set 14a has a circuit board 141a and a plurality of LEDs 142a located on the circuit board 141. The light-guiding plate 12a is received in the reflection cover (not shown in the figure) The LED set 14a is located on the reflection cover and corresponds to the light-entering surface 120a of the light-guiding plate 12a. In the light-guiding structure of the prior art, the LED set 14a emits light and the light emits into the light-entering surface 120a of the light-guiding plate 12a. The light is refracted and reflected, and emits from the light-emitting surface 121a of the light-guiding plate 12a. 
However, because each of the LEDs (the spontaneous light source) is a point-shaped light source, a fluorescence symptom (the brightness on a single point is larger occurs, and the illumination of the fluorescence generated by each of the LEDs 142a is higher than the other area. Therefore, a bright point is generated at the light-entering surface 120a of the light-guiding plate 12a, and the light emitted from the light-emitting surface 121a is not uniform. It does not meet the requirement for the backlight device.